STRUCTURES OF 4 N-BENZOYLAZIRIDINE AND AZIRIDINIUM P-TOLUENESULFONATEDERIVATIVES GRAFTED ONTO 7-OXABICYCLO[2.2.1]HEPTANE SKELETONS

Dimethyl 3-benzoyl-8-oxa-3-azatricyclo[3.2. 1.0(2,4)]-octane-6,7-dicar boxylate (7), C17H17NO6, M(r) = 331.33, monoclinic, P1(1)/c, a = 5.362 (1), b = 24.558(3), c = 11.793(1) angstrom, beta = 96.42(1)-degrees, V = 1543 (1) angstrom, Z = 4, D(x) = 1.43 g cm-3, lambda(Mo Kalpha) 0. 70930 angstrom, mu = 1.0 cm-1, F(000) = 696, T 123 (1) K, R = 0.047 fo r 1743 unique observed reflections. 6,7-Dimethoxycarbonyl-8-oxa-3-azo- niatricyclo[3.2. 1.0(2,4)]octane p-toluenesulfonate (14), C17H21NO8S, M(r) = 399.42, monoclinic, P2(1)/c, a = 14.160(4), b = 5.514(1), c = 2 3.792(7) angstrom, beta = 100.16 (2)-degrees, V = 1828 (2) angstrom3, Z = 4, D(x) 1.45 g cm-3, lambda(Mo Kalpha) = 0.70930 angstrom, mu = 2. 1 cm-1, F(000) = 840, T = 193 (1) K, R = 0.045 for 2737 unique observe d reflections. arbonyl-8-oxa-3-azoniatricyclo[3.2.1.0(2,4)]octane p-to luenesulfonate (18), C17H21NO8S, M(r) = 399.42, monoclinic, P2(1)/n, a = 21.501 (6), b = 5.476 (2), c 15.858 (2) angstrom, beta = 90.68 (2)- degrees, V = 1867 (i) angstrom3, Z = 4, D(x) = 1.42 g cm-3 lambda(Mo K alpha) 0.70930 angstrom, mu = 2.1 cm-1, F(000) 840, T = 123 (1) K, R = 0.029 for 1680 unique observed reflections. -6-cyano-8-oxa-3-azatricy clo[3.2.1.0(2,4)]oct-6-yl acetate (19), C16H14N2O4, M(r) = 298.30, tri clinic, P1BAR, a = 5.654 (1), b = 8.088 (3), c = 16.223 (7) angstrom, a = 103.78 (3), beta = 90.35 (3), gamma = 98.29 (2)-degrees, V = 712 ( i) angstrom3, Z = 2, D(x) 1.39 g cm-3 lambda(Mo Kalpha) = 0.70930 angs trom, mu = 0.9 cm-1, F(000) = 312, T = 294 (1) K, R = 0.040 for 2021 u nique observed reflections. The crystal structures of the aziridinium salts (14) and (18) and of the N-benzoylaziridine derivatives (7) and (19) have been established by X-ray diffraction. The data are discusse d in the light of proposed mechanisms for the acid-catalysed rearrange ment of aziridine derivatives of 7-oxabicyclo[2.2.1]heptane diesters a nd compared with predictions from quantum mechanical calculations on a ziridine and the aziridinium ion. The most striking observation is tha t the endo carboxylate group of salt (18) does not interact with the C centers of the aziridinium moiety. This result suggests that, contrar y to common postulates, little positive charge resides on the C center s of aziridinium ions in their ground state.